This invention relates to a magnetic orthodontic appliance through which corrective traction is applied to teeth of a patient by magnetically generated force derived from permanent magnets in order to correct the positions of the teeth.
Conventional orthodontic appliances using magnetic traction for producing corrective displacement of the patient's teeth have the following defects:
(1) The corrective traction force is not enough to produce corrective displacement of the patient's teeth in practice. It is not convenient to use a magnet having a thickness as great as 3.2-3.5 mm is in the mouth.
(2) It is difficult to adjust the magnetic force or corrective force while viewing the teeth to be corrected.
(3) Corrective movement of the teeth is limited to one direction (a mesiodistal direction). Accordingly, three-dimensional movement of the teeth is almost impossible.
(4) Before a magnet is fixedly mounted on a tooth, the magnet easily moves toward the adjacent magnet through magnetic traction. For that reason, an orthodontist must press the magnet against the tooth until the bonding agent hardens so that the magnet is completely fixed thereto.
(5) When the patient bites, a magnet is often broken due to its large size.
(6) It is difficult to remove the magnets for adjustment of the corrective force.
(7) A correcting or ligature wire must be tightened or strengthened by repeated adjustments by a dentist for the purpose of adjustment to the proper corrective force.